As the swine production industry has evolved from the status of a supplement to farm income to that of a mojor enterprise with production in intensified units, modern confinement facilities for the hogs and pigs have been developed. These facilities require the application of increasingly refined principles of breeding, nutrition, physiology, and environmental control so that the hogs can be developed to economically produce the maximum quality products. With respect to swine management, the primary object is to minimize environmental factors which are adverse to the swine so as to provide maximum opportunity for survival and growth.
Particularly during farrowing, a large number of pigs in the litter fail to survive for finishing or breeding as a result of crushing by the sow, infections, or starvation. Thus, climatically controlled farrowing houses or facilities with specially adapted farrowing pens have been employed to minimize the losses from the litter. Typically, the sow is confined within a central pen portion of the farrowing pen or crate, which is only large enough to permit her to recline on her side. Side pens of the farrowing crate adjacent each side of the central pen accommodate the litter, and a divider forming the adjacent sides of the central and side pens prevents the sow from entering the side pens and injuring the litter. The pigs in the litter, however, can obtain access to the sow for feeding by passing under the divider, and thereby, the pigs can move to either side of the sow as is required.
In the usual arrangement for an animal shelter of this farrowing house type, two rows of pens are provided along the length of the shelter, with the pens placed in a side-by-side arrangement adjacent each other. A center aisle between the rows provides access to the pens, and side aisles at the rear of the pens can also be included. The flooring of the shelter, which supports the pens and animals, is typically raised above the ground surface so as to form a pit beneath the flooring. Furthermore, the flooring is usually slotted to permit passage of the animals' waste through to the pit below. The slotted floors not only reduce or practically eliminate floor cleaning, but also greatly retard the spread of disease and parasites by allowing the rapid removal of excrement from the pens. Additionally, the slotted floor is an essential component in controlling the atmospheric environment of the farrowing house, in that air is circulated downwardly through the slots to control the temperature and diffusion of odors.
The survival and development of the litter and sow within a confinement facility of this type is dependent on proper control of ambient temperatures within the facility. A newborn pig is dependent on supplemental heat from the environment since it is incapable of maintaining its own body temperature. On the other hand, sows must be protected from exposure to high temperatures, since they have very limited ability to dissipate body heat by sweating. Typically, it is desirable to maintain a temperature of 80.degree. F. for newborn pigs, while the surrounding temperature for the sow is perferably maintained at 65.degree. F. Thus, any supplemental heat provided for the litter can adversely affect the sow if exposure to the heat occurs.
Prior methods of supplying supplemental heat for the litter have incorporated independent heating systems that direct radiant or convective heat toward the litter. Thus, in some facilities, heat lamps are positioned above the litter or pen in which the litter is contained. The inefficiency of radiant and convective heat supplied in this manner diminishes the economy of production. Furthermore, supplemental heat provided in this manner is not easily controlled to maintain the desirable temperature, and inadvertent heating of the sows cannot always be avoided.
Other methods of supplying supplemental heat to the litter have incorporated systems for heating the entire farrowing house. As shown in U.S. Pat. to Jones et al. No. 4,018,271, U.S. Pat. to Jones et al. No. 3,826,230, U.S. Pat. to Becker No. 3,815,550, and U.S. Pat. to Jones et al. No. 3,809,014, these heating systems adapt the flooring of the facility for circulation of a heated fluid through the flooring whereby heat is supplied by conduction and radiation. In a typical construction there is provided a slotted floor composed of individual slats positioned in a parallel spaced arrangement and supported at their opposite ends. The slats, which have been formed from precast concrete, aluminum, or thermoplastic materials, include conduits that are embedded within each individual slat for circulation of a heated fluid through the slat. The conduits are interconnected to form a continuous system, and thereby the complete surface of the flooring is heated as heat is conducted from the fluid. These systems do not allow selective heating of the litter alone, and detrimental heating of the sow cannot be avoided.
Furthermore, construction of the flooring for farrowing houses or facilities has been substantially simplified in recent years with the development of floor sections containing a plurality of slats and which are integrally formed by casting reinforced concrete. A representative product of this type is shown in Stevenson, U.S. Pat. No. 3,905,334. These integral floor sections are commonly referred to as gang slats. The gang slats are supported at opposite ends on the peripheral and center walls of the farrowing house in a manner similar to the installation of the individual slats, but there is an additional advantage in that installation is convenient. So far as can be determined, no one has heretofore provided any type of built-in heating means with gang slats and with which this invention is particularly concerned.